BAGHDAD, Iraq -

A suicide bomber killed more than 30 people Wednesday in a cafe northeast of Baghdad, and three American soldiers died when a roadside bomb exploded northwest of the capital, authorities said.

The bomber blew himself up in a restaurant in Balad Ruz, 45 miles northeast of Baghdad, a police officer said on condition of anonymity. Dozens were wounded, he said.

The U.S. soldiers were killed by the roadside bomb as they patrolled a well-traveled route northwest of Baghdad to clear it of explosives, the military said. Nine soldiers died in two separate attacks on Monday -- the deadliest single day for Americans in Iraq in nearly a month.

Attacks on Shiite pilgrims showed no sign of easing, with at least 11 slain as they streamed toward a Muslim shrine ahead of a weekend holiday.

The violence came a day after two suicide bombers exploded themselves among pilgrims lining up at a checkpoint, killing at least 120 people and wounding about 190, police and hospital officials said.

Mourners carried coffins through Hillah, about 60 miles south of Baghdad, where a main street became a swamp of blood and debris after Tuesday's twin attack. Bodies in plastic bags were lined up outside the city's hospital, where the wounded lay on gurneys in crowded hallways.

The Hillah bombings and other attacks on Shiites have been blamed on Sunni insurgents trying to destabilize Iraq's Shiite-dominated government.

The victims had been headed to Karbala, 50 miles south of Baghdad, for weekend rites marking the end of a 40-day mourning period for the death of Imam Hussein, the grandson of the Prophet Muhammad. Hussein died near Karbala in a 7th century battle.

Abbas Ghatie Ali, a 32-year-old pilgrim walking from Baghdad to Karbala on Wednesday, tied a list of emergency contacts around his neck in case he was hurt along the way.

"I'm wearing this card to identify me if I'm killed during the journey to Karbala," Ali said. He said he would continue to walk despite attacks on fellow pilgrims, because Shiites are "the majority and will defend our ideology and doctrine."

Another pilgrim, Khadija Tawfek Mouhsin, said his brother was killed last year en route to Karbala, but that he was determined to make the journey. "The terrorists give us the chance to go to paradise," the 39-year-old Shiite pilgrim said.

Community leaders in Karbala met to discuss how to better provide security for the pilgrims, according to a statement from Prime Minister Nouri al-Maliki's office. The Defense Ministry said Tuesday it would deploy soldiers along the pilgrimage route.

"All the city's entrances have been secured, and I call upon the pilgrims to follow the instructions of the security forces and let them do the necessary searches," Iraq's minister of state for national security, Sherwan al-Waili, said in Karbala.

"Terrorists are adapting and improvising new ways of hurting people. Preparations have been made in hospitals to receive emergency cases," he said.

Karbala Gov. Aqeel al-Khazalie said 10,000 policeman had been deployed in the city.

The head of the Supreme Council for Islamic Revolution in Iraq, Abdul Aziz al-Hakim, condemned the Hillah bombings and called for more government security during the holiday.

"We call on the security services of the central government and the local authorities ... to chase the masterminds who carry out these ugly crimes," al-Hakim said.

Al-Maliki on Tuesday called the Hillah bombings an "ugly crime against unarmed citizens" that "would not pass without punishment."

But some Shiite leaders have expressed anger at the government for not doing enough to prevent the killings. "The government bears some responsibility for this," complained Shiite lawmaker Bahaa al-Araji. "It has not provided enough security to protect the pilgrims."

In the past two years, the powerful Mahdi Army militia of radical cleric Muqtada al-Sadr watched over pilgrimages to Karbala. But the group agreed to put down its arms under intense pressure from the government, which wanted to avoid any confrontations with U.S.-led forces during a Baghdad security crackdown launched last month.

"This year, things are sadly different," said al-Araji.

The commander of U.S. troops in Iraq, Gen. David Petraeus, and U.S. Ambassador Zalmay Khalilzad issued a joint statement expressing "outrage at the cowardly and brutal acts of violence" against pilgrims.

"This heinous and brutal act demonstrates the lengths to which extremists will go in their attempts to terrorize devout Iraqi people," they said. "But the terrorists will not prevail. Make no mistake; Iraqi forces and their Coalition partners are committed to the security and safety of all Iraqis."

In other violence Wednesday, a suicide car bomb killed eight people and wounded at least 23 at a police checkpoint in southwest Baghdad, police said. Three of the dead were police commandos, they said.

A police lieutenant and his 15-year-old son were also shot to death in their car late Tuesday on a road in Diwaniyah, 80 miles south of Baghdad, police said. In Ramadi, the provincial capital of western Anbar province, masked gunmen killed a butcher in his shop, police said.

The biggest attack on pilgrims Wednesday occurred in Dora, a mostly Sunni neighborhood of southern Baghdad, where a roadside bomb killed at least seven people, police said. Immediately after the blast, gunmen fired on the victims. About 14 were wounded, they said.

Hours later, pilgrims continued to stream through the neighborhood, stepping over spent ammunition that littered a main thoroughfare.

Gunmen also opened fire on Shiite pilgrims on a bridge in southeastern Baghdad, killing three and wounding five, police said. Another shooting left one pilgrim dead and four wounded in central Baghdad, police said.

Also Wednesday, Iran's foreign minister said his government would send a delegation to an international conference in Baghdad this weekend. The conference of Iraq's neighbors and the permanent members of the U.N. Security Council will be the first public encounter between U.S. and Iranian envoys since late 2004.

"We hope the conference will result in sending a clear message that the countries of the region are standing alongside the government and nation of Iraq," Manouchehr Mottaki said in Tehran.

Earlier this week, Mottaki said his government was finalizing its decision on whether to attend. He indicated that Iran was in favor of participating but it had reservations.

Iran's delegation will be led by the deputy foreign minister for legal and international affairs, Abbas Araghchi, Mottaki said.